Antihypertensives direct-acting vasodilators

Systemic heat Large whirlpool Hubbard tank Decreased muscle/joint stiffness in large areas of the body Opioid and nonopioid analgesics skeletal muscle relaxants Severe hypotension may occur if systemic hot whirlpool is administered to patients taking peripheral vasodilators and some antihypertensive drugs (eg., alpha-1 antagonists, nitrates, direct-acting vasodilators, calcium channel blockers)... 

Diazoxide is a parenteral, rapid, and direct-acting vasodilating antihypertensive used in hypertensive emergencies. An IV injection can drop blood pressure by as much as 80 mmHg in 5 minutes. Unlike sodium nitroprusside, however, venous dilation is not part of its mechanism. Chemically it is a benzothiadiazide without the sulfamoyl function at the 7 position (see diuretics). In fact, diazoxide is not a diuretic. Chronic use of diazoxide reflexly increases renin release, which actually counteracts the antihypertensive effect of the drug by expanding the volume of circulating fluid. 

The vasodilators decrease total peripheral resistance and thus correct the hemodynamic abnormality that is responsible for the elevated blood pressure in primary hypertension. In addition, because they act directly on vascular smooth muscle, the vasodilators are effective in lowering blood pressure, regardless of the etiology of the hypertension. Unlike many other antihypertensive agents, the vasodilators do not inhibit the activity of the sympathetic nervous system therefore, orthostatic hypotension and impotence are not problems. Additionally, most vasodilators relax arterial smooth muscle to a greater extent than venous smooth muscle, thereby further minimizing postural hypotension. 

Direct vasodilators frequently produce baroreflex-induced tachycardia, but rarely orthostatic hypotension. They are usually prescribed with a beta blocker or a centrally acting antihypertensive to minimize the reflex increase in heart rate and cardiac output. It should be noted that another member of the directly acting class of antihypertensives is minoxidil. This potent, long-acting drug has gained considerable notoriety for its use as a topical hair-restorer. Oral use can result in hirsutism (unwanted hair growth over the face as well as other parts of the body). 

Antihypertensive Vasodilators - A common characteristic of hypertensive patients, regardless of the etiology of their disease, is abnormally high peripheral vascular resistance. Drugs that act directly on peripheral vasculature to decrease resistance are, therefore, logical agents for the treatment of hypertension. Unfortunately, sympathetic reflex actions leading to cardiac stimulation, hyperreninemia and fluid retention limit the hypotensive action of vasodilators and they are used mainly in combination with 6-blockers and diuretics for the treatment of more severe hypertension. A vasodilator that may not cause undesirable reflex... 

---